JPEG (Joint Photographic Experts Group) 2000 is known as an encoding method wherein, in the event of performing image (data) encoding, coefficients of sub-bands (frequency bands) generated by performing band division processing on an input image are encoded.
In the event of encoding an image with JPEG 2000, wavelet coefficients obtained by performing wavelet transformation on the input image are quantized, and the quantized coefficients obtained by quantizing are further subjected to entropy encoding.
Conventionally, with entropy encoding, bit modeling called EBCOT (Embedded Block Coding with Optimized Truncation) and arithmetical encoding called MQ coder are performed. That is to say, quantized coefficients are subjected to bit modeling, and further subjected to arithmetical encoding based on multiple coding paths for each bit plane. The code obtained by the arithmetical encoding is output as an encoded image (data) (e.g., Patent Document 1).
Also, in the event of decoding an image encoded by JPEG 2000, processing is performed with procedures opposite to the case of encoding. More specifically, the code which is the encoded image data is subjected to entropy decoding an inverse quantization, and the quantized coefficients obtained thereby are further subjected to wavelet inverse transformation. The image obtained by the wavelet inverse transformation is output as a decoded image.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2004-166254